Many could crumble if struck hard enough in the right spot

10:47 PM,
May 25, 2013

A section of the Interstate 5 bridge over the Skagit River collapsed Thursday in Washington state.

Written by

Mike Baker
and Joan Lowy

Thousands of bridges around the United States may be one freak accident or mistake away from collapse, even if the spans are deemed structurally sound.

The crossings are kept standing by engineering design, not supported with brute strength or redundant protections like their more modern counterparts. The consequence of that risk was evident Thursday on Interstate 5 over the Skagit River, where a large section of the bridge collapsed into the water, officials say after an oversized truck load clipped the steel truss.

While the truck's cargo suffered only minimal damage, it left chaos in ...